diff --git a/ale_linters/c/cppcheck.vim b/ale_linters/c/cppcheck.vim
index b2ded90f..309b2851 100644
--- a/ale_linters/c/cppcheck.vim
+++ b/ale_linters/c/cppcheck.vim
@@ -5,20 +5,17 @@ call ale#Set('c_cppcheck_executable', 'cppcheck')
 call ale#Set('c_cppcheck_options', '--enable=style')
 
 function! ale_linters#c#cppcheck#GetCommand(buffer) abort
-    " Search upwards from the file for compile_commands.json.
-    "
-    " If we find it, we'll `cd` to where the compile_commands.json file is,
-    " then use the file to set up import paths, etc.
-    let [l:dir, l:json_path] = ale#c#FindCompileCommands(a:buffer)
-    let l:cd_command = !empty(l:dir) ? ale#path#CdString(l:dir) : ''
-    let l:compile_commands_option = !empty(l:json_path)
-    \   ? '--project=' . ale#Escape(l:json_path[len(l:dir) + 1: ])
+    let l:cd_command = ale#handlers#cppcheck#GetCdCommand(a:buffer)
+    let l:compile_commands_option = ale#handlers#cppcheck#GetCompileCommandsOptions(a:buffer)
+    let l:buffer_path_include = empty(l:compile_commands_option)
+    \   ? ale#handlers#cppcheck#GetBufferPathIncludeOptions(a:buffer)
     \   : ''
 
     return l:cd_command
     \   . '%e -q --language=c'
     \   . ale#Pad(l:compile_commands_option)
     \   . ale#Pad(ale#Var(a:buffer, 'c_cppcheck_options'))
+    \   . l:buffer_path_include
     \   . ' %t'
 endfunction
 
diff --git a/ale_linters/cpp/cppcheck.vim b/ale_linters/cpp/cppcheck.vim
index dae0774e..7cd80dbc 100644
--- a/ale_linters/cpp/cppcheck.vim
+++ b/ale_linters/cpp/cppcheck.vim
@@ -5,20 +5,17 @@ call ale#Set('cpp_cppcheck_executable', 'cppcheck')
 call ale#Set('cpp_cppcheck_options', '--enable=style')
 
 function! ale_linters#cpp#cppcheck#GetCommand(buffer) abort
-    " Search upwards from the file for compile_commands.json.
-    "
-    " If we find it, we'll `cd` to where the compile_commands.json file is,
-    " then use the file to set up import paths, etc.
-    let [l:dir, l:json_path] = ale#c#FindCompileCommands(a:buffer)
-    let l:cd_command = !empty(l:dir) ? ale#path#CdString(l:dir) : ''
-    let l:compile_commands_option = !empty(l:json_path)
-    \   ? '--project=' . ale#Escape(l:json_path[len(l:dir) + 1: ])
+    let l:cd_command = ale#handlers#cppcheck#GetCdCommand(a:buffer)
+    let l:compile_commands_option = ale#handlers#cppcheck#GetCompileCommandsOptions(a:buffer)
+    let l:buffer_path_include = empty(l:compile_commands_option)
+    \   ? ale#handlers#cppcheck#GetBufferPathIncludeOptions(a:buffer)
     \   : ''
 
     return l:cd_command
     \   . '%e -q --language=c++'
     \   . ale#Pad(l:compile_commands_option)
     \   . ale#Pad(ale#Var(a:buffer, 'cpp_cppcheck_options'))
+    \   . l:buffer_path_include
     \   . ' %t'
 endfunction
 
diff --git a/autoload/ale/handlers/cppcheck.vim b/autoload/ale/handlers/cppcheck.vim
index dc56cd0b..6d8fa15d 100644
--- a/autoload/ale/handlers/cppcheck.vim
+++ b/autoload/ale/handlers/cppcheck.vim
@@ -1,5 +1,46 @@
 " Description: Handle errors for cppcheck.
 
+function! ale#handlers#cppcheck#GetCdCommand(buffer) abort
+    let [l:dir, l:json_path] = ale#c#FindCompileCommands(a:buffer)
+    let l:cd_command = !empty(l:dir) ? ale#path#CdString(l:dir) : ''
+
+    return l:cd_command
+endfunction
+
+function! ale#handlers#cppcheck#GetBufferPathIncludeOptions(buffer) abort
+    let l:buffer_path_include = ''
+
+    " Get path to this buffer so we can include it into cppcheck with -I
+    " This could be expanded to get more -I directives from the compile
+    " command in compile_commands.json, if it's found.
+    let l:buffer_path = fnamemodify(bufname(a:buffer), ':p:h')
+    let l:buffer_path_include = ' -I' . ale#Escape(l:buffer_path)
+
+    return l:buffer_path_include
+endfunction
+
+function! ale#handlers#cppcheck#GetCompileCommandsOptions(buffer) abort
+    " If the current buffer is modified, using compile_commands.json does no
+    " good, so include the file's directory instead. It's not quite as good as
+    " using --project, but is at least equivalent to running cppcheck on this
+    " file manually from the file's directory.
+    let l:modified = getbufvar(a:buffer, '&modified')
+
+    if l:modified
+        return ''
+    endif
+
+    " Search upwards from the file for compile_commands.json.
+    "
+    " If we find it, we'll `cd` to where the compile_commands.json file is,
+    " then use the file to set up import paths, etc.
+    let [l:dir, l:json_path] = ale#c#FindCompileCommands(a:buffer)
+
+    return !empty(l:json_path)
+    \   ? '--project=' . ale#Escape(l:json_path[len(l:dir) + 1: ])
+    \   : ''
+endfunction
+
 function! ale#handlers#cppcheck#HandleCppCheckFormat(buffer, lines) abort
     " Look for lines like the following.
     "
diff --git a/test/command_callback/test_c_cppcheck_command_callbacks.vader b/test/command_callback/test_c_cppcheck_command_callbacks.vader
index 8e11ef2d..7f1a7c2f 100644
--- a/test/command_callback/test_c_cppcheck_command_callbacks.vader
+++ b/test/command_callback/test_c_cppcheck_command_callbacks.vader
@@ -1,9 +1,15 @@
 Before:
   call ale#assert#SetUpLinterTest('c', 'cppcheck')
 
-  let b:command_tail = ' -q --language=c --enable=style %t'
+  let b:command_tail = ' -q --language=c --enable=style -I' . ale#Escape(ale#path#Simplify(g:dir)) .' %t'
 
 After:
+  " Remove a test file we might open for some tests.
+  if &buftype != 'nofile'
+    :q!
+    set buftype=nofile
+  endif
+
   call ale#assert#TearDownLinterTest()
 
   unlet! b:command_tail
@@ -15,17 +21,15 @@ Execute(The executable should be configurable):
 
   AssertLinter 'foobar', ale#Escape('foobar') . b:command_tail
 
-Execute(cppcheck for C++ should detect compile_commands.json files):
-  call ale#test#SetFilename('cppcheck_paths/one/foo.cpp')
+Execute(cppcheck for C should detect compile_commands.json files):
+  call ale#test#SetFilename('cppcheck_paths/one/foo.c')
 
   AssertLinter 'cppcheck',
   \ ale#path#CdString(ale#path#Simplify(g:dir . '/cppcheck_paths/one'))
   \   . ale#Escape('cppcheck')
-  \   . ' -q --language=c'
-  \   . ' --project=' . ale#Escape('compile_commands.json')
-  \   . ' --enable=style %t'
+  \   . ' -q --language=c --project=''compile_commands.json'' --enable=style %t'
 
-Execute(cppcheck for C++ should detect compile_commands.json files in build directories):
+Execute(cppcheck for C should detect compile_commands.json files in build directories):
   call ale#test#SetFilename('cppcheck_paths/with_build_dir/foo.cpp')
 
   AssertLinter 'cppcheck',
@@ -34,3 +38,27 @@ Execute(cppcheck for C++ should detect compile_commands.json files in build dire
   \   . ' -q --language=c'
   \   . ' --project=' . ale#Escape(ale#path#Simplify('build/compile_commands.json'))
   \   . ' --enable=style %t'
+
+Execute(cppcheck for C should include file dir if compile_commands.json file is not found):
+  call ale#test#SetFilename('cppcheck_paths/foo.cpp')
+
+  AssertLinter 'cppcheck',
+  \   ale#Escape('cppcheck')
+  \   . ' -q --language=c'
+  \   . ' --enable=style'
+  \   . ' -I' . ale#Escape(ale#path#Simplify(g:dir . '/cppcheck_paths'))
+  \   . ' %t'
+
+Execute(cppcheck for C should ignore compile_commands.json file if buffer is modified):
+  call ale#test#SetFilename('cppcheck_paths/one/foo.c')
+
+  set buftype=
+  set modified
+
+  AssertLinter 'cppcheck',
+  \   ale#path#CdString(ale#path#Simplify(g:dir . '/cppcheck_paths/one'))
+  \   . ale#Escape('cppcheck')
+  \   . ' -q --language=c'
+  \   . ' --enable=style'
+  \   . ' -I' . ale#Escape(ale#path#Simplify(g:dir . '/cppcheck_paths/one'))
+  \   . ' %t'
diff --git a/test/command_callback/test_cpp_cppcheck_command_callbacks.vader b/test/command_callback/test_cpp_cppcheck_command_callbacks.vader
index 15c8c4b8..13b0741e 100644
--- a/test/command_callback/test_cpp_cppcheck_command_callbacks.vader
+++ b/test/command_callback/test_cpp_cppcheck_command_callbacks.vader
@@ -1,8 +1,14 @@
 Before:
   call ale#assert#SetUpLinterTest('cpp', 'cppcheck')
-  let b:command_tail = ' -q --language=c++ --enable=style %t'
+  let b:command_tail = ' -q --language=c++ --enable=style -I' . ale#Escape(ale#path#Simplify(g:dir)) .' %t'
 
 After:
+  " Remove a test file we might open for some tests.
+  if &buftype != 'nofile'
+    :q!
+    set buftype=nofile
+  endif
+
   unlet! b:command_tail
   call ale#assert#TearDownLinterTest()
 
@@ -19,9 +25,7 @@ Execute(cppcheck for C++ should detect compile_commands.json files):
   AssertLinter 'cppcheck',
   \ ale#path#CdString(ale#path#Simplify(g:dir . '/cppcheck_paths/one'))
   \   . ale#Escape('cppcheck')
-  \   . ' -q --language=c++'
-  \   . ' --project=' . ale#Escape('compile_commands.json')
-  \   . ' --enable=style %t'
+  \   . ' -q --language=c++ --project=''compile_commands.json'' --enable=style %t'
 
 Execute(cppcheck for C++ should detect compile_commands.json files in build directories):
   call ale#test#SetFilename('cppcheck_paths/with_build_dir/foo.cpp')
@@ -32,3 +36,27 @@ Execute(cppcheck for C++ should detect compile_commands.json files in build dire
   \   . ' -q --language=c++'
   \   . ' --project=' . ale#Escape(ale#path#Simplify('build/compile_commands.json'))
   \   . ' --enable=style %t'
+
+Execute(cppcheck for C++ should include file dir if compile_commands.json file is not found):
+  call ale#test#SetFilename('cppcheck_paths/foo.cpp')
+
+  AssertLinter 'cppcheck',
+  \   ale#Escape('cppcheck')
+  \   . ' -q --language=c++'
+  \   . ' --enable=style'
+  \   . ' -I' . ale#Escape(ale#path#Simplify(g:dir . '/cppcheck_paths'))
+  \   . ' %t'
+
+Execute(cppcheck for C++ should ignore compile_commands.json file if buffer is modified):
+  call ale#test#SetFilename('cppcheck_paths/one/foo.cpp')
+
+  set buftype=
+  set modified
+
+  AssertLinter 'cppcheck',
+  \   ale#path#CdString(ale#path#Simplify(g:dir . '/cppcheck_paths/one'))
+  \   . ale#Escape('cppcheck')
+  \   . ' -q --language=c++'
+  \   . ' --enable=style'
+  \   . ' -I' . ale#Escape(ale#path#Simplify(g:dir . '/cppcheck_paths/one'))
+  \   . ' %t'
diff --git a/test/handler/test_rstcheck_lint_handler.vader b/test/handler/test_rstcheck_lint_handler.vader
index 3b4ac037..c65c15eb 100644
--- a/test/handler/test_rstcheck_lint_handler.vader
+++ b/test/handler/test_rstcheck_lint_handler.vader
@@ -1,36 +1,42 @@
 Before:
-  runtime ale_linters/rstcheck/rstcheck.vim
+  runtime ale_linters/rst/rstcheck.vim
 
 After:
   call ale#linter#Reset()
 
 Execute(Warning and error messages should be handled correctly):
+  " For some reason we can't set the directory such that the filenames are
+  " correct here when running the tests from the Docker image, so we have to
+  " just check the basenames of the files instead.
   AssertEqual
   \ [
   \   {
-  \      'filename': ale#path#Simplify(expand('%:p:h') . '/bad_python.rst'),
+  \      'filename': 'bad_python.rst',
   \      'lnum': 7,
   \      'col': 0,
   \      'type': 'W',
   \      'text': '(python) unexpected EOF while parsing',
   \   },
   \   {
-  \      'filename': ale#path#Simplify(expand('%:p:h') . '/bad_cpp.rst'),
+  \      'filename': 'bad_cpp.rst',
   \      'lnum': 9,
   \      'col': 0,
   \      'type': 'W',
   \      'text': '(cpp) error: ''x'' was not declared in this scope',
   \   },
   \   {
-  \      'filename': ale#path#Simplify(expand('%:p:h') . '/bad_rst.rst'),
+  \      'filename': 'bad_rst.rst',
   \      'lnum': 1,
   \      'col': 0,
   \      'type': 'E',
   \      'text': 'Title overline & underline mismatch.',
   \   },
   \ ],
-  \ ale_linters#rst#rstcheck#Handle(1, [
-  \   'bad_python.rst:7: (ERROR/3) (python) unexpected EOF while parsing',
-  \   'bad_cpp.rst:9: (ERROR/3) (cpp) error: ''x'' was not declared in this scope',
-  \   'bad_rst.rst:1: (SEVERE/4) Title overline & underline mismatch.',
-  \])
+  \ map(
+  \   ale_linters#rst#rstcheck#Handle(1, [
+  \     'bad_python.rst:7: (ERROR/3) (python) unexpected EOF while parsing',
+  \     'bad_cpp.rst:9: (ERROR/3) (cpp) error: ''x'' was not declared in this scope',
+  \     'bad_rst.rst:1: (SEVERE/4) Title overline & underline mismatch.',
+  \   ]),
+  \   'extend(v:val, {''filename'': fnamemodify(v:val.filename, '':t'')})'
+  \ )